Influence of Ca2+, K+ and NO3-fertilisation on nutritional quality of pepper

A study was conducted in order to assess the effect of different fertilisation levels of Ca2+, K+ and NO3- on the bioactive nutrient content in red pepper (Capsicum annuum L) fruits. The experiment was carried out in a greenhouse, under hydroponic culture. Lycopene, beta-carotene, vitamin C, total phenolic compound, sugar, nitrate and potassium contents and antioxidant activity were determined. Increasing Ca2+ and NO3- concentrations in the root medium increased the lycopene and beta-carotene contents in pepper. Antioxidant activity was determined in the hydrophilic (HAA) and lipophilic (LAA) fractions. HAA was increased by intermediate and high Ca2+ concentrations in the culture medium. However, LAA was raised only by NO3- treatments. Vitamin C, sugar and total phenolic acid contents were not affected by Ca2+ or NO3- treatments. K+ treatments had no effect on nutritional quality of pepper. An increased supply of Ca2+ and NO3- in the culture medium could constitute a useful practice for improving the nutritional attributes of pepper as well as its commercial quality. (C) 2004 Society of Chemical Industry.